A number of machines, illustrated by a plurality of United States patents, for example, the Thomas E. Andrako U.S. Pat. No. 3,855,969, have been developed to create an extended blanket of development material against a surface bearing an electrostatic latent image to be developed. Such development apparatus is surrounded by a housing which provides a sump into which the development material can fall and wherein mixing takes place, with fresh toner particles to replace those toner particles taken out of the magnetic mix by the image.
Unfortunately, the magnetic particles of the developer mix are very fine and are subject to mechanical abuse. If mechanical abuse reduces the nature of the magnetic material to a dust, the charge must be removed and replaced with fresh, new material.